Reamers are tools used in orthopedic procedures to cut bone and associated tissue matter. Specifically, the cutting head of the present invention are designed to cut and bore into the intramedullary space or inner canal of a long bone such as a femur, tibia or humerus. Typically, the intramedullary space of a long bone is reamed to clean and create a space for an implant. As such, these reamers are required to be sterile and sharp. Using a dull reamer generates heat that typically leads to tissue necrosis and results in undesirable patient outcomes. A non-sterile reamer blade typically results in an infected and damaged intramedullary space that may lead to other problems for the patient.
Reamers are often used in trauma procedures. In one such procedure, a prosthetic implant is inserted into the intramedullary space to help mend a fractured bone. In the procedure, a flexible reamer is first inserted into the intramedullary space of the fractured bone. Using the intramedullary reamer, a cavity space is then formed for insertion of the implant into the fractured bone.
The preparation of the bone generally consists of removing the interior contents of the bone along its entire length so that a space is created allowing for insertion of the intramedullary nail. The removal of the interior contents occurs in steps, where a cutting head having a relatively small cutting diameter is used to initiate a pilot hole and removal of the medullary contents. A series of cutting heads having progressively larger cutting diameters is then used to further increase the diameter of the intramedullary space and remove more bone and tissue material. The surgeon typically continues to use reamer cutting heads of increasing diameter until the appropriately sized space is created. After the appropriate sized space is created, an intramedullary nail is typically installed within the space to assist in the healing of the traumatized bone.
However, prior art cutting heads have an inefficient blade design which tends to become increasingly dull, particularly when reaming large portions of bone material within a long bone, such as a femur. Furthermore, because of their high cost, traditional cutter heads are typically reused multiple times. Over time, as these reamer heads are used and reused, the cutting blades become dull. As a result, these less efficient prior art cutting heads tend to promote an increase in “head pressure” within the intramedullary canal. “Head pressure” is the pressure that forms ahead of the reaming bone cutter within the intramedullary canal. Increasing head pressure within the intramedullary canal may result in the occurrence of a “fat” embolism. A fat embolism occurs when fat becomes lodged within a blood vessel and obstructs blood flow. The occurrence of a fat embolism may result in a stroke or even death to the patient.
The intramedullary cutting head of the present invention, therefore, is designed to cut bone and tissue more efficiently than the cutting heads of the prior art. In contrast to the prior art, the cutting head blades are designed to reduce reactive torque and axial load while cutting, thus reducing trauma to the bone while cutting within the intramedullary space. In addition, the cutting head of the present invention is designed to efficiently remove cut material and debris so that the debris unobstructedly flows over the cutting head. Thus “head pressure” and the possibility of producing a fat embolism within the intramedullary canal is reduced.
Unfortunately, there is no simple way to evaluate cutting efficiency after these reamer tools have been used and reused. Many times it isn't until the surgeon has reused the reamer numerous times that he becomes aware that the reamer is cutting incorrectly. In many cases, an ineffective, dull, or contaminated reamer tool is not detected until well into the reaming procedure or even after the procedure is complete. Good surgical outcomes are largely dependent on the use of a sharp, sterile reamer that is in optimal condition. Poor surgical outcomes such as a damaged intramedullary space can occur as a result of using dull or contaminated reamers.
Accordingly, the present invention provides an embodiment of a cutting head having a novel blade and assembly design that improves cutting efficiency within the intramedullary space. The enhanced reaming efficiencies of the present invention decrease procedural times and minimize patient trauma. Furthermore, the intramedullary cutting head of the present invention ensures sharpness and cleanliness that promotes optimal patient outcomes.